In impact tools disclosed in the aforesaid patents, the energy stored in a spring is released to rotate an inertia or mass member which impacts against a tool head to rotate the latter when driving connections between the inertia member and tool head are brought into rotative alignment. A considerable amount of the stored energy in the spring is dissipated in overcoming friction and, therefore, reducing the effective output of the tool. In the tool disclosed in the Swenson U.S. Pat. No. 2,954,714, the frictional losses occur as a result of side loadings on the pivotal connections of the thrust link and crosshead assembly, which interconnects the inertia member and spring. In the tool disclosed in the patent to Swenson, U.S. Pat. No. 3,108,506, the side loadings on the spring and the curved push rod which is disposed within the coils of the spring and interconnects the inertia member and spring, results in frictional losses between the spring and push rod. Also, because of side loadings, frictional losses occur between the spring and a stiffening rod which extends within the spring coils to prevent buckling of the spring as well as between the spring and a guard trough which confines lateral movement of the spring. Therefore, these impact tools, to deliver impact forces of a specified magnitude, have to be made larger to compensate for the frictional losses than would be required if those losses were substantially reduced.
Accordingly, it is an object of the present invention to provide a manually actuated impact tool capable of providing greater impact force than impact tools of like type and of comparable size.
It is another object of this invention to provide a manually actuated impact tool of relatively simple construction, of high efficiency, and improved reliability.